1. Field of the Invention
This invention relates to a microresonator including a beam-type oscillator which is electrostatically driven, a band-pass filter using this microresonator, a semiconductor device having this microresonator, and a communication apparatus using a band-pass filter based on this microresonator.
2. Description of the Related Art
In recent years, micro-oscillator elements (microresonator elements) manufactured using micromachine (MEMS: Micro-Electro-Mechanical Systems) technology have become well known. A microresonator element manufactured using semiconductor processes occupies a device small area, is capable of high Q values, and can be integrated with other semiconductor devices. With these features, applications as high-frequency filters in wireless communication device have been proposed by Michigan University and other research institutes (see Non-patent Reference 1).
Configurations are also known in which a plurality of microresonator elements are arranged in parallel to form a microresonator, for use as a high-frequency filter. Further, it is known that microresonators having different resonance frequencies can be interconnected to broaden the pass band of the filter.
However, when microresonators having different resonance frequencies are interconnected, ripple voltages occur between the microresonators, and the problem arises that the higher the Q value of the microresonators, the higher are the ripple voltages. It is known that in order to lower the ripple voltages, the Q values of the microresonators are lowered.
Hence configurations are known in which microresonator elements with different resonance frequencies are combined to form a microresonator, with the Q values of the microresonator lowered.
Non-patent Reference 1: C. T.-Nguyen, Micromechanical components for miniaturized low-power communications (invited plenary), Proceedings, 1999 IEEEMTT-S International Microwave Symposium RF MEMS Workshop, Jun. 18, 1999, pp. 48-77.